CHAPTER TOOLS

Keywords:

density estimation methods;

detectability functions;

kernel estimation;

line transects;

narrow-strip method;

point transects;

smooth-by-eye method;

variable circular plots

Summary

This chapter looks first at some of the density estimation methods that can be used with line transect data, initially without regard to the sampling procedure for selecting transects. The methods include narrow-strip method and smooth-by-eye method. It then examines different designs for selecting a sample of transects. For estimating the variance of the population density estimators, estimators relying on sampling procedures rather than model assumptions about the population are emphasized. The chapter examines some underlying ideas about sampling and estimation with line transects. It also covers estimators based on individual detection probabilities. The chapter gives some general results on design and estimation in terms of detectability functions. It then presents variable circular plots or point transects in which the observer is stationary for a specified amount of time at each selected site and locations or distances associated with detections are recorded.